Rotator Cuff 101

     The term rotator cuff gets thrown around in the gym and in sports quite frequently. Unfortunately, not many people know what it is and what it does until it is injured. We’re going to go over what the rotator cuff is, what it is responsible for, and what happens when it is injured.

            The rotator cuff is a group of muscles and tendons that surround the shoulder joint, keeping the head of your upper arm bone firmly within the shallow socket of the shoulder. It is comprised of 4 individual muscles, each with a different function. These are the supraspinatus, infraspinatus, teres minor, and subscapularis. Each of these muscles originates at a unique space on the shoulder blade and attaches to the humerus (upper arm bone). Without getting too in depth with functions; these muscles allow you to rotate the shoulder while keeping the head of the humerus in its socket. Each of these muscles are deeper within the shoulder and not as prominent as the larger deltoid muscles that we can see. Even though they are smaller, they must possess an equal amount of strength and endurance as the larger muscles around it to support daily functions.

Muscle Name                                                                      Function

Supraspinatus                                                         Abduction of the Humerus

Infraspinatus                                                           External rotation of humerus

Teres Minor                                                              External rotation of humerus

Subscapularis                                                          Internal rotation of humerus


             The muscles of the rotator cuff are difficult to isolate and strengthen like “normal” muscles. You can train the deltoid or the pectoralis for hypertrophy and strength while the rotator you cannot as easily. Externally and internally rotating the shoulder against resistance can help to train and strengthen the individual muscles. I prefer to use resistance bands to do this as there is near constant resistance against it. When doing overhead or horizontal pressing the rotator cuff is a stabilizer muscle that is keeping the shoulder joint in place and is activated and helping press to some degree. With the combination of these two methods, the muscles of the rotator cuff can be strengthened. When compared with other stabilizing muscles, the rotator is quite strong and possesses a great deal of endurance.

 Internal rotation of the shoulder, one of the functions of the rotator cuff

Internal rotation of the shoulder, one of the functions of the rotator cuff

            One of the issues with being such an important, functional part of the body is the injuries that can occur. Just like any other injury, the severity can range from just a strain to losing function of the shoulder. Rotator cuff impingement syndrome occurs when the tendons of these muscles, particularly the supraspinatus and infraspinatuss, become irritated and inflamed as they move. This results in pain, weakness, and loss of movement at the shoulder. This could cause the shoulder joint to become impinged as the joint becomes unstable. Another common issue seen in the rotator cuff is an imbalance between the left and right side. This is commonly seen in athletes that primarily use one arm to a greater degree than the other (i.e. Baseball). We see a lot of injuries to the rotator cuff in baseball, especially pitchers. Swimmers are also affected by injuries to the rotator.

 Pitchers in baseball are especially prone to rotator cuff injuries

Pitchers in baseball are especially prone to rotator cuff injuries

            To prevent injury and keep the rotator cuff healthy we have to use a couple strategies. The concept of “prehab” can be applied here. A simple definition of prehab is treating pain and injury before they even occur. This proactive approach means strengthening and stabilizing a certain muscle or area of the body. Together with flexibility, balance, and ensuring proper function of the joint means injuries can be prevented or at least limited in severity. A proper warm up and being smart about not overloading the joints over and over are the best strategies we can take. Being wary of our posture (not rolling our shoulder forward when we’re typing on the computer) can also be a factor in our rotator cuff health. If a prior injury has happened, these strategies become that more important. Being aware of your body and knowing your limits helps. More severe injuries call for a more intensive, medical approach. Tears usually result in some kind of surgery with long recovery times.

            As you can tell, the rotator cuff is an important part your everyday activities and is engaged anytime you move your arm. By using some of the strategies above, hopefully the risk of injuries goes down and we keep our shoulders healthy.


Floyd, R. (2012). Manual of Structural Kinesiology. New York: McGraw Hill.